ProjectSummary/Abstract With an aging population and increased life span, the number of patients requiring reconstructive joint surgeries or joint replacements continues to increase. Many patients undergoing arthroplasty procedures suffer from bone disorders such as osteoporosis, severe arthrosis or osteopenia, with a bony matrix that impedesfirmanchoringofimplantstoexistingbone.Thisresultsinpoorimplantosseointegrationandaseptic loosening, and requires revision surgeries in many patients. The need and opportunity exists for new therapeuticstrategiesthatimprovebone-implantcontactanddeviceosseointegration. Theobjectiveoftheproposedprojectistodiscoversmallmoleculeinhibitorsofthehistonemethyltransferase enhancer of zeste homolog 2 (EZH2) that can be incorporated in the surface coating of a model titanium devicesubstrate.Uponreleasefromthesubstrate,thesecompoundswillstimulateosteogenicdifferentiation of mesenchymal stem cells (MSCs) at the device/tissue interface, promoting bone growth and device osseointegration. Dr. Andre van Wijnen of Mayo Clinic and others have demonstrated that EZH2 inhibitors stimulate bone formation by decreasing epigenetic inhibition of the Wnt/?-catenin signaling pathway. The research described in the current proposal will demonstrate that EZH2 inhibitors, when incorporated into hydroxyapatite surface coatings of titanium disks, will enhance osteogenic differentiation of human MSCs culturedonthedisksasmeasuredbyrelevantbiomarkersandimmunohistochemicalstaining. Successful completion of this Phase I SBIR feasibility study will form the basis for a program directed at the developmentofadrug/devicecombinationproductthatwillgreatlyenhanceimplantosseointegration,reduce the need for revision surgeries, and be convenient and cost effective with respect to manufacturing and preparations required by surgical staff. Relative to orally or parenterally administered compounds, local delivery of bone pro-anabolic EZH2 inhibitors at the device/tissue interface will minimize systemic exposure and toxicity, specifically myelosuppression observed for EZH2 inhibitors currently in development for the treatmentofcancer. TheprojectleveragesthecomplementaryknowledgeandcapabilitiesofNumerate,Inc.andDr.vanWijnen?s laboratory.Dr.vanWijnenhasextensivelycharacterizedtheeffectsofEZH2inhibitiononboneformation,and has significant experience with assays that assess growth and integration of MSCs with titanium device substrates.Numerate?steamisexperiencedinsmallmoleculedrugdiscoveryanddevelopment,andwillapply its ligand-based, AI-driven small molecule drug design platform to the design and optimization of EZH2 inhibitorsforuseincoatedorthopedicimplants.